# HEY: MX records and email verification

How HEY and HEY for Domains addresses look in DNS, how HEY answers a verification handshake, and which verdicts to expect for hey.com and custom domains.

Updated: 2026-09-03

HEY is the email service from 37signals, launched in 2020 with a screening-first design: mail from a new sender is held in a screener until the recipient lets it through. It serves personal accounts on hey.com and company domains through HEY for Domains. Spaw reports both as `mx_provider: "hey"`.

## How HEY shows up in DNS

hey.com publishes a single MX record, `home-mx.app.hey.com`, and HEY for Domains customers point their MX at hosts under the same `hey.com` zone, which HEY displays during setup. Spaw matches the `.hey.com` suffix. HEY is a mailbox host: the MX target is HEY's own inbound infrastructure, `mx_found` is true and `mx_implicit` is false.

## How HEY answers a verification handshake

HEY typically rejects unknown recipients at `RCPT TO`, so a missing hey.com mailbox is confirmed in the session. The screener is a feature of the inbox, not of the SMTP conversation: a message to an existing address is accepted by the server whether or not the recipient has approved the sender, and the screening happens afterwards. HEY for Domains does not expose a conventional catch-all setting, so catch-all answers are uncommon on HEY domains. Deferrals are rare but possible for sources HEY has not seen.

## What that means for your verdicts

HEY addresses mostly come back `deliverable` with `mailbox_exists: true` or `undeliverable` with `reason: mailbox_not_found` and `smtp_reason: no_mailbox`. Occasional unverified probes show `smtp_reason: greylisted` with `mailbox_confidence` returned; HEY is not on the established-provider list, so the estimate depends on the domain's own records and the username's shape. There are no consumer username rules for hey.com in Spaw's rule set, and hey.com usernames are short by design because HEY sold them on a first-come basis, so `is_gibberish` is more often true on real HEY addresses than elsewhere and should be read as a hint only.

A `deliverable` verdict on a HEY address is a statement about the mailbox, not about reach: a first message from an unknown sender lands in the screener and is only seen if the recipient chooses to see it.

## SPF and DMARC at HEY

HEY for Domains shows the SPF, DKIM and DMARC records to publish during domain setup and asks for the MX to be switched only at the final step, so existing mail keeps flowing until the switch. HEY does not publish a public DNS reference page for these values, so copy them from the setup screen rather than from third-party guides. hey.com itself publishes SPF and a DMARC policy. Spaw reports the live state of any domain in `has_spf` and `dmarc_policy`.

## Practical notes for sending to HEY users

Expect low engagement from cold outreach: the screener means unsolicited mail is rarely read, and HEY users can block a sender permanently with one click. Transactional mail from services the user signed up for is approved once and then delivered normally. HEY for Domains customers are small companies, so role addresses exist and are flagged `risky` with `reason: role` as usual. HEY supports plus-style addressing for personal accounts through its own aliasing, which a verifier sees as ordinary addresses.

For a live look at any HEY-hosted domain, run it through the free MX lookup and the SPF and DMARC checker.

Reference: https://spaw.co/email-providers/hey